Derivative Instruments - Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivative financial instruments
Derivative assets	$ 772	$ 0
Designated as hedging instruments:
Derivative financial instruments
Derivative liabilities	781	2,536
Not designated as hedging instruments:
Derivative financial instruments
Derivative assets	10,344	5,977
Derivative liabilities	4,532	3,503
Other Assets | Designated as hedging instruments: | Interest rate swaps
Derivative financial instruments
Derivative assets	772	0
Other Assets | Not designated as hedging instruments: | Interest rate contracts
Derivative financial instruments
Derivative assets	4,370	3,171
Other Assets | Not designated as hedging instruments: | Interest rate lock commitments
Derivative financial instruments
Derivative assets	4,309	2,756
Other Assets | Not designated as hedging instruments: | Forward commitments
Derivative financial instruments
Derivative assets	1,665	50
Other Liabilities | Designated as hedging instruments: | Interest rate swaps
Derivative financial instruments
Derivative liabilities	781	2,536
Other Liabilities | Not designated as hedging instruments: | Interest rate contracts
Derivative financial instruments
Derivative liabilities	4,370	3,171
Other Liabilities | Not designated as hedging instruments: | Interest rate lock commitments
Derivative financial instruments
Derivative liabilities	83	4
Other Liabilities | Not designated as hedging instruments: | Forward commitments
Derivative financial instruments
Derivative liabilities	$ 79	$ 328